QuantativeChemisty Flashcards
What is reletive formula mass
The sum of all the atomic masses of an element in a compound
What is the empirical formula
Simplest whole ratio of the elements in a compound e.g. CO2
1 carbon 2 oxygen
How to work out the empirical formula
Get masses of elements in compound and divide each of them by their atomic masses. Divide the answers by the smallest answer to find the simplest ratio and write it down
What is percentage mass
The percentage of a mound of mass an element in a compound uses
How to work out percentage mass
Number of atoms of the element in compound x atomic mass of the element over the reletive formula mass of the compound x 100
Work out percentage yield
Actual yield over theoretical yield x 100
What is the relative atomic mass of an element
The mass of an atom of an element compared to carbon 12
E.g hydrogen is twelve times lighter to hydrogen = 1
What is the difference between empirical formula and molecular formula
Empirical formula is the simplified molecular formula. Molecular formula is the true amount of atoms of an element in the compound. E.g. Molecular formula of ethene and propène is C2H4 and C3H6 but the empirical formula of both is CH2
How to work out theoretical yield.
Calculate relative formula masses of each element. Add them
What causes actual yield to be less than theoretical yield
Reaction may not be finished
May be other unwanted reactions taking place which uses the reactants
Some of the reactant is loss during preparation such as in spillages.
What are waste products
Useless by products of a reaction that can’t be sold and need to be disposed of
